A nerf was not unwarranted- AP Corki had too much damage combined with too much range+escape ability. If there's one thing Riot doesn't like, it's strong champions with no counterplay. However: Riot, if you're reading this, keep the ult damage nerf, but please bring back the CDR scaling on his ults!

AP Corki is no longer overpowered/competitively viable. I'm 3-0 so far, so while he may be a troll pick he is at least a viable troll pick.

Sorry for the weirdly formatted guide- it was written before the website update, and I'm not gonna bother a rewrite considering AP Corki's sorry state.

I'll leave the rest of the guide untouched below. R.I.P., godly one.

_____________________________________

After the patch 3.9 buffs, I went on a 7-0 streak and then 32-13 as my main while obtaining Diamond. That's a 71% winrate, which is insane. It was over 80% until I hit promos. AP Corki is sleeper OP right now, check it out!

Flask is the best non-blade start because of its sustain, but there are many options (see item section). Similarly to Kennen, Corki can start Doran's Blade to bully melees and many other lanes. Like Kennen, Corki has strong autos, weak pre-6 AP scaling, and a big escape. An 800 range escape makes a starting ward usually unnecessary.

Core: or / /

If you value MR, Athene's is just as gold efficient as Morellonomicon in addition to giving near-blue buff independency.

Summoner Sets

Primary Set

Barrier
Keeps you alive long enough for you to finish off the opponent or for Valkyrie to come off cooldown. I take it on AP Corki for the same reason I take it on an ADC- you have more burst and longer range, but are still a squishy, sustained damage carry. Except against extremely skilled opponents, people will rarely account for this, so it is a valuable tool for baiting the enemy; you can go all-in and use this at the last minute, or use it to block the last ranged attack as your opponent fires off what they think will be the last needed. Just be careful to not use it too late.

Flash
Best spell in the game. I suppose its not absolutely necessary on Corki due to having Valkyrie, but take it anyways. Its nice to be able to flash in, deal damage, then valkyrie away (or vice versa). Alternatively, you can use them in the same direction to cover extremely long distances, both escaping and pursuing enemies. Valkyrie can be interrupted by CC, so it's very good to have a secondary, more reliable escape. Also note that flash is instant and uninterruptable, making it more useful than Valkyrie for dodging skillshots.

Cleanse & Flash

God. Damn. Fiddle. Fear.
Cleanse plus Valkyrie can get you out of pretty much anything, so this is a solid option against lanes/teamcomps with strong CC. It might be the best overall summoner spell for those who are used to it and can react instantaneously to CC- I merely dislike it personally, because I've never bothered to develop the reaction time on it to make it worth using over barrier except in a few cases. This is a high skillcap spell, yet generally isn't better than a straightforward barrier- even pro AD Carries don't run cleanse anymore.

Ignite & Flash

Ignite
I'd take this over barrier in a lane where I had more kill potential than the enemy. This also helps you respond better to jungler ganks, especially before level 6 when your DPS is weak. This is less useful lategame than barrier or cleanse, as it will be more important to stay alive to output DPS, and the range is pretty short. It can be used to finish off the enemy, but is better used at the very beginning of an all-in combo so that you can judge your damage properly, and receive the 5 AD and AP bonus from the Summoner's Wrath mastery (make sure to take this one!). If you don't expect an immediate kill, it is sometimes good to use ignite right away when your laner drinks a health potion- this is good harass gives you the Summoner's Wrath bonuses, and reduces their healing. If you run ignite, make sure to use it in a teamfight against Dr. Mundo, Swain, or another burst healer.

Upgrade Valkyrie (W) second. This lowers the cooldown to make you safer in lane and skirmishes, and increases the damage to wraiths/waves/people chasing you. You can delay this until level 4 if you feel safe in lane (e.g. vs Warwick jungle) but there's really no point in doing so.

Take one point in Gatling Gun (E) at level 8 or 10, and then max it last. The armor shred provides utility, and this does deal some physical damage, but its more important to lower your Valkyrie cooldown. Furthermore, you would rather spend the mana on another skill, so taking it at level 4 is not advised.

Obviously, take your ult (R) whenever it is available. It is far and away your strongest skill, and upgrading it both lowers the cooldown on missile stacks and increases the damage. You will have a huge power spike whenever you upgrade your ult (6/11/16)- communicate this to your team.

Skills

Hextech Shrapnel Shells

You won't build enough AD to make this relevant. 10% Better lasthitting OP. Will provide between 4.8 and 10.2 damage onhit, and an extra 1 damage from Doran's.

Phosphorus Bomb

This skill is really good. Large AoE at a nice range. Harass with this. Waveclear with this.

Note that this is not affected by a line of creeps. If facing, for example, a Lee Sin or Ezreal, know that you can use your Q while they can't retaliate with theirs. It also means that you can farm and harass at the same time if the enemy is positioned properly.

This skill provides vision, so use it to facecheck bushes and before/after somebody runs into a bush (6 seconds is a long time!).

As of patch 3.9, this skill has a significantly higher mana cost than your ultimate (6 times more!), so if you are low on mana keep spamming your ultimates while avoiding Q's.

Valkyrie

Flash is 400 range. This is 800 goddamn range. Nerf please.

If your opponent doesn't have flash up, you can use this range to give the enemy laner no idea that your jungler is coming to gank by staying back then jumping in on them from afar. You can also try to jump over them, doing a little extra damage in 1v1 or gank scenarios.

A good strategy with AP Corki is to quickly clear the wave, and then use Valkyrie to roam or jump onto your wraith camp (or your opponent's) to clear it almost instantly. This skill can also be used to shove the lane.

If people are chasing you, try to force them to walk over or around this. It's damage is really good, especially once you have some AP.

Be aware that this isn't instantaneous, therefore can be interrupted mid-flight by any sort of CC. For example, I have died because I tried to Valkyrie away from a Zac slingshot, and he knocked me up right as I began my flight.

Gatling Gun

Pretty insignificant for AP Corki. When you have surplus mana, might as well activate it and do a bit more damage close range.

Note that it shreds armor quite a bit, especially at max rank, so be sure to have it on when your AD teammates are dealing damage and when getting in range is not dangerous.

Note that this has a range slightly higher than your auto-attack, so you can use it for that last bit of damage while chasing.

Missile Barrage

NOTE: Some of this info is incorrect since the CDR nerfs

Soooo good. Tons of AoE damage. Low scaling, but high base damages on a short cooldown make this build possible. With a completed 20% CDR item or blue buff, Corki can easily bully an opponent out of lane without them even getting in range to do damage. A single E-R combo at level 6 will clear any group of minions, and R-R will clear the caster minions. Use this skill to soften up opponents before a fight, but make sure not to run out of stacks early. If you have trouble landing ults, consider buying an early Rylai's.

Make sure to note when you have a Big One ready, as the damage and radius of AoE is significantly higher. In lane, you can use this to harass a champion hiding behind their minions.

At level 16 with 40% CDR, you get a new missile every 4.8 seconds and can release your stored 7 (33 second cooldown) in five seconds flat for a sweet 2280 + 2.45% AP pre-mitigation AoE damage, not counting even two Phosphorus Bombs and another rocket you'll have saved up by then. Sweet.

Introduction

Sup.

I'm Tinkady, an NA player currently in Diamond V. I like to theorycraft and am good at it. If you disagree with anything I say in this guide, or have any new ideas, let me know and I can do some math.

First off: AP Corki is not a troll build. I usually have the most damage dealt to champions in the game, usually don't feed, and usually win. AP Corki's full level 16 combo has a 33 second cooldown and does 3009+380% AP damage over six seconds (see mathcrafting section for calculations). Thus, building AP is viable, but it is even better to forgo AP and stack Magic Penetration and Cooldown Reduction.

Yes, AP Corki is viable in ranked. AP Corki offers huge AoE dps and poke, and fits into any teamcomp that has CC. I was 4-4 with AP Corki in ranked before the patch 3.9 buffs (and I'm 0-2 with AD Corki, hence the edits to my win/loss). Afterwards, I went on a 7-0 streak, and went 34-13 while reaching Diamond. That's a 72% winrate, which is insane considering I'm where I deserve to be. He is also a 100% safe blind pick because AP Corki has literally no counters, only even/riskier matchups.

I picked up AP Corki after seeing this video on Reddit. Go watch it. It's funny and informative, even though he uses an outdated build.

I'm a fan of poke champions in solo queue overall, because they are countered by organized initiation, which is more often seen in pro play. I've had particular success using poke champions with mobility tools- AP Corki, AP Nidalee, and pre-nerf Jayce.

My main before AP Corki was AP Kog'maw (see http://www.solomid.net/guides.php?g=36515-rudgimusmaximus-kogmaw-build-guide where I helped theorycraft the build). AP Corki is literally just easymode AP Kog. Corki has less range in exchange for a very strong laning phase and an 800 distance escape/gapcloser (flash is only 400). AP Kog is strong but risky due to his ramp-up time and immobility, and AP Corki is a risk-free blind pick that takes much less time to affect the game and carries almost as hard.

Pros

Extremely strong poke and sustained AoE DPS

Pretty good burst, especially midgame

No counters. Literally no counters. Safe first pick

Almost impossible to die/be denied farm

Quick waveclear + wraiths farming

Mobile- able to chase/gapclose quickly

Good at sieging towers with poke

Turtles well by clearing waves from long distance

Safe against most divers

In draft mode, people will counterpick you as an ADC

Snowballs hard if fed before MR is built

Blue buff independent (although they are helpful)

Helicopter

Cons

Mediocre pre-6 sustained DPS

No CC until Rylai's/not much utlity

No sustain (but can farm without taking harass post-6)

Corki is powerful throughout the game and a good passive farmer when necessary yet able to play stupidly aggressive with minimal risk. Played correctly, you should never die, while doing... tons of damage.

You can also take AP Corki toplane, and this has recently gained some popularity in Diamond/Challenger. Corki doesn't desperately need blue buff, and Corki can bully quite a few melees, especially with a Doran's Blade start. I'd recommend taking a flask to toplane, since your lack of sustain is even more significant there, and likely won't get blue buffs. The biggest downsides are that Valkyrie isn't as effective in a long lane, your easy wraith farming is unavailable, blue buffs are usually given to mid, tanks can be hard to force out of lane, and your team may be too squishy with a standard AP mid.

But Corki has shitty AP scalings, right? Yes, but he still scales extremely well overall using this build. As proof of concept, here's some endgame math (approximate) comparing this and the build from the above AP Kog guide:

The damage is almost identical, and AP Kog is one of the biggest lategame hypercarries around. Kog has a longer range and probably does more damage overall, but sucks early and is terrible against divers whereas Corki can usually win laning phase and is hard to lock down. AP Corki can definitely be considered a hypercarry.

AP Corki carries games. Don't knock it till ya try it.

Why not AD Corki?

Note: This section is temporarily outdated, as AD Corki is currently overpowered due to being the best trinity force user. I'll see how much the upcoming Trinity Force nerfs affect AD Corki, then revisit this section.

I much prefer AP Corki to AD Corki. Besides his mana problems (much better since patch 3.9), my primary problem with AD Corki is that mid/lategame, especially if I'm losing, I'd rather spam missiles than get in my short autoattack range. However, missiles don't scale all that well with AD- they scale best with magic penetration, CDR, and AP (in that order).

Corki has huge base damages on his Q and R that are amplified by magic pen, and in lane, poke, or extended teamfight scenarios his DPS is heavily tied to CDR. His AP ratios aren't great, but when trying to increase missile damage, considering the gold cost of AD and AP it is (.3 AP scaling) / (20 gold per AP) * (.2 AD scaling) / (34.4 gold per AD) = 2.58 times better to buy AP than AD).
(source: http://www.reignofgaming.net/blogs/a-different-view/vvinrar/22455-all-about-season-3-item-efficiency)

Also consider Karthus's AP ratios- 0.3/0.6, 0.2, and 0.6. Why is he a hypercarry? Because his damage is AoE and on a very short cooldown, just like Corki.

More evidence that AP Corki is superior to AD Corki can be seen in item winrates, collected on 9/14/2013:
http://www.elophant.com/league-of-legends/champion/corki/items?region=all&tier=all&period=month

AD items:

Berserker's Greaves: 54%

Trinity Force: 56%

Bloodthirster: 55%

Last Whisper: 54%

Infinity Edge: 56%

AP items:

Sorcerer's Shoes: 57%

Athene's Unholy Grail: 57%

Void Staff: 74%

Liandry's Torment: 67%

Rylai's Crystal Scepter: 66%

The sample sizes on AP items are low, but the general trend is unmistakable. AP Corki is a stronger pick than AD Corki.

Masteries

Setup 1:
I run this and rune page 1 whenever I don't start with a Doran's Blade.

This is definitely a strong choice, especially if you have CDR glyphs. It is safe and scales better into lategame, but offers less early bullying potential.

Take a point out of Summoner's Wrath or Summoner's Resolve depending on which summoner spell you are running. Run Hardiness or Resistance depending on if your lane opponent is AP or AD. The points in offense are self-explanatory, other than forgoing Archmage (doesn't really offer much) in favor of Brute Force and Butcher, for better early harass and easier last-hitting. Feel free to modify this page, I haven't extensively theorycrafted it- I often run setup 2.

Setup 2 :
I run this with a Doran's Blade start and rune page 2.

The 9 in offensive is for the 4% CDR and 8% Magic pen. Our two favorite stats, and definitely necessary.

The following are core in utility: Summoner's insight, Meditation, Mastermind, Biscuiteer, Awareness, Intelligence, and Nimble. We can use our summoners more often, have more CDR, extend blue buffs, more quickly reach the level 6/11/16 power spikes, have extended buff duration, and are a bit faster.

9/0/21 is viable even if not starting with Doran's. In this case, I recommend taking the 3 points out of Vampirism and placing them into Greed (or Explorer). If not planning on taking blue buffs, skip Runic Affinity.

The most important part about the 9/0/21 page is that it gives us 10% CDR from masteries alone. This lets us hit the all-important 40% CDR with only a 20% item and a 10% item or blue elixir.

6 CDR glyphs is pretty random, and was chosen because it comes out to an even 4%.
This page caps out at 39% CDR with DFG and no blue buff. Getting to 40 would require two more glpyhs, rather than one, and is probably not worth it. Plus, CDR glyphs are freakin' expensive, and I want to keep my recommendations accessible. Even though I don't build 40% CDR without blue anymore, having some starting CDR is just a good idea since it so heavily ties into your damage.

Marks: Mpen or Hybrid Pen
Magic pen is very strong with Corki's base damages. If you own them, and are starting with Doran's, hybrid penetration marks are a possibility. Magic pen is so good on Corki that I definitely wouldn't go out of my way to use hybrids. Hybrids are only superior when more than 30% of damage is physical, if I remember correctly, and I don't believe that is the case here.
Other options: AD

Glyphs: Men or MR or CDR
Magic pen is the most effective offensive rune for this slot (feel free to prove me wrong with math). Corki has such a strong escape that it isn't necessary to take any defensive stats at all. However, MR is a good idea against tough AP lanes, or champs with a long enough range to trade with you even after 6 (Lux, Xerath, etc). However, we can easily build MR through Athene's, so MR glyphps are generally unnecessary. CDR glyphs are a solid alternative choice, as they can replace the utility tree as a source of 10% CDR, and I am currently considering a switch over to Ajido's 21/9/0 setup using these glyphs.
Other options: MR/level, AP/level, Armor

Seals: Armor or Gp10
Armor seals are standard on pretty much anybody. They're gold efficient, and even an AP will do physical damage through autoattacks and minion aggro. However, if you don't think you'll have troubles surviving earlygame, AP Corki generally doesn't need defensive stats. If not in danger, or against an AP lane and jungle, I recommend Gp10 seals- investment banking OP.
Other options: Mp5, Health/level

Quints: AD or Mpen or Gp10
AD runes are a good option if taking the Doran's Blade route, or just planning to auto-attack a lot. I also like using one lifesteal quint for extra sustain. When not starting with Doran's because I plan to play more passively, I take gold quints for that sweet, sweet cash flow. These are extremely efficient (see mathcrafting section). If not starting Doran's but still want early power, run magic penetration quints. These also scale far better into lategame than AD quints. There is absolutely no reason to take AP quints- Corki has only a single 0.5 AP ratio pre-6.
Other options: Lifesteal, MS, Hybrid Pen, Spell Vamp

Summoner Spells

Explanation:

Barrier
Keeps you alive long enough for you to finish off the opponent or for Valkyrie to come off cooldown. I take it on AP Corki for the same reason I take it on an ADC- you have more burst and longer range, but are still a squishy, sustained damage carry. Except against extremely skilled opponents, people will rarely account for this, so it is a valuable tool for baiting the enemy; you can go all-in and use this at the last minute, or use it to block the last ranged attack as your opponent fires off what they think will be the last needed. Just be careful to not use it too late.

Flash
Best spell in the game. I suppose its not absolutely necessary on Corki due to having Valkyrie, but take it anyways. Its nice to be able to flash in, deal damage, then valkyrie away (or vice versa). Alternatively, you can use them in the same direction to cover extremely long distances, both escaping and pursuing enemies. Valkyrie can be interrupted by CC, so it's very good to have a secondary, more reliable escape. Also note that flash is instant and uninterruptable, making it more useful than Valkyrie for dodging skillshots.

Also good:

Ignite
I'd take this over barrier in a lane where I had more kill potential than the enemy. This also helps you respond better to jungler ganks, especially before level 6 when your DPS is weak. This is less useful lategame than barrier or cleanse, as it will be more important to stay alive to output DPS, and the range is pretty short. It can be used to finish off the enemy, but is better used at the very beginning of an all-in combo so that you can judge your damage properly, and receive the 5 AD and AP bonus from the Summoner's Wrath mastery (make sure to take this one!). If you don't expect an immediate kill, it is sometimes good to use ignite right away when your laner drinks a health potion- this is good harass gives you the Summoner's Wrath bonuses, and reduces their healing. If you run ignite, make sure to use it in a teamfight against Dr. Mundo, Swain, or another burst healer.

Cleanse
God. Damn. Fiddle. Fear.
Cleanse plus Valkyrie can get you out of pretty much anything, so this is a solid option against lanes/teamcomps with strong CC. It might be the best overall summoner spell for those who are used to it and can react instantaneously to CC- I merely dislike it personally, because I've never bothered to develop the reaction time on it to make it worth using over barrier except in a few cases. This is a high skillcap spell, yet generally isn't better than a straightforward barrier- even pro AD Carries don't run cleanse anymore.

Viable:

Exhaust
This could work for some more CC/peel if your support is taking ignite and you want an exhaust on the team. This spell can be used offensively, using the slow as a form of CC. However, its primary strength would be to kite and reduce the damage of divers on you and your ADC. This is especially effective against auto-attacking assassins, such as Zed, because it reduces both overall damage output and attack speed. I see no reason to take this over barrier, but it is indeed an option.

Teleport
You are already very mobile with Valkyrie, but could take this to apply even more global pressure. I wouldn't recommend this, for several reasons. Since you don't build very much AD, attack speed, or AP, you solo push towers very slowly. Your primary goal is to poke down the other team, thus shouldn't be splitpushing lategame. In general, teleport is a good option if you don't expect to get kills or die (farm lane) or want to counter your laner's roam.

Item Builds

Aggressive Start: (with rune+mastery setup #2)

Defensive starts: (with rune+mastery setup #1) + / / + / / + /

Much like Kennen, AP Corki has the option to start out AD and then transition into AP because of his similarly weak pre-6 AP scaling. This improves your Q-Auto harass, assuming you pair bombs with at least one auto, and provides some very nice sustain. Paired with Vampirism and Biscuteer masteries, and an optional Lifesteal quint, you can survive early lane by simply falling back and autoing when taken low. On the flip side, this start is risky against unsafe lanes, whether this is because they are able to assasinate you or harass you from afar.

Doran's provides more DPS and bullying potential (especially vs. melees), and survivability from the base heath. However, Doran's is not viable in dificult lanes, and instead I prefer double charm and pots for more mana, an earlier Athene's, and safe potion sustain.

Start Doran's when you can bully (Veigar, most melees, etc). Reconsider this start if they can outtrade you at auto range (Cassiopeia, Kayle, etc) or gapclose and kill you without their ultimate (Fizz, Pantheon, etc) or outrange you early (Lux, Xerath, etc).

An 800 range escape makes starting with a ward usually unnecessary- consider the lane and jungle matchup.

or
CDR and a baseline level of mana regeneration is essential on Corki, to maximize spamming of missiles and rockets, thus we build one of these items. Athene's is no longer mandatory after patch 3.9 due to Corki's reduced mana costs. However, it is still very good as it offers equal gold efficiency to Morellonomicon (assuming you value MR) as well as blue buff independence. Morellonomicon is 400g cheaper and offers an additional 300g of AP, but Athene's offers more mana regen and 800g of magic resistance. Therefore, get Athene's unless you do't need the magic restance and you are getting blue buffs. When buying Morellonomicon, get Kage's first if playing passively and Codex first if playing aggressively.

/
These are the best earlygame magic penetration items around, and synergize highly with Corki's high base damages. I'd say these are required in every single game. If you need more defenses, Haunting Guise is a strong source of health to rush, and only in extreme cases would I replace Sorcerer's Shoes with Mercury's Treads (fed Kassadin).

Void gives extreme spell penetration and brings your overall percentage MR reduction to 40%. Since we have high base damages and low ratios, this increases DPS much more than a Deathcap would. This is strong even against non-tanks. You reduce their MR by less, but we are pairing this with high flat MPen, and getting closer to 0 MR stacks multiplicatively. Damage is proportional to: (base damage) / [100+MR*(% pen)-(flat pen)]

Liandry's gives spell pen and increases base damages. It also comes with health, which is not the strongest stat on AP Corki, but having some defense is good so that you're not instantly blown up.Buy this first if your opponents are stacking health without MR. This item is strongest in poke situations, but substantially increases your burst as well.

Rylai's gives some survivability from a large amount of health. More importantly, it increases your damage from AP (there are no more good magic pen items to buy). It also provides some crowd control to help poke/kite/peel/chain ults, and turns you engage and disenage from long distances. The slow from Rylai's also doubles the burn damage from Liandry's, making Rylai's almost as much of a damage increase as a Deathcap at this point in the build. Corki's abilities only apply the reduced 15% slow because they are AoE, but this is still nice because your ults are AoE and long range. Rylai's is a cost-efficient item even without the slow, which is very beneficial to Corki, so is a very good purchase.

This is the quintissential damage item for AP's, but less efficient for Corki than others. However, with maxed CDR Corki's AP ratios are actually not bad due to low cooldowns, and this is usually the best 6th item choice. Deathcap increases your offensive power similarly to DFG- Deathcap has 8% more damage, but DFG is cheaper, has 10% CDR, and has 10% more single-target burst with the active.

Deathfire provides 10% CDR as well as lots of AP and an active that drastically increases your single-target burst (see mathcrafting section) and amplifies your already high damage. Corki should usually be out of range to use this active, but 750 range isn't too shabby, and it is useful whenever making a catch or fending off a diver. Build this out of your early fiendish codex if you aren't receiving blue buffs, in order to max out your CDR.

This is a good early item if you need the mana regen (building Morellonomicon or not receiving blue buffs) and don't want a flask. It's no good as a starting item, since you don't need pre-6 AP, but it's solid as a first back. This is also a good item to pick up if you are behind, as it is very cost-effective and gives early survivability and mana to farm with spells.

An early cloth armor or Armguard is not a bad idea if against a hard AD mid. This can be turned into Zhonya's later, or sold if winning. I'm not a huge fan of Zhonya's on Corki, but it's definitely a good situational pick. If the biggest threat to your survival is a fed Talon/Zed/Jarvan/Karthus/etc, then go ahead and pick one up.

If struggling vs. heavy AP, pick one of these items up at any point in the game. A giant's belt is the ideal choice to mitigate burst damage because it builds into Rylai's, but better to buy these as well than get blown up immediately by a hyper-fed Leblanc.

Guardian Angel is the best defensive item against mixed damage. This is a good 6th item when carrying, as it deters focus. If the enemy CC + burst + gapclose is just too damn high, get this item. Depending on the situation, you can Valkyrie away upon respawn, or may just get bursted down if your team is not with you.

As a general note: even while building glass cannon, Corki will die less frequently than most champions. Liandry's+Rylai's gives 800 health, not much less than a Warmog's, and allows you to kite effectively. Try not to rely on any other defensive items.

Whenever you have some extra cash, don't forget to buy these. Vision OP. You may be better at escaping than most, but it's still a good idea to help you and your team avoid getting caught, and vision can win teamfights because your team will have a better idea of when it's safe to engage and safety from flanking assassins.

After you finish core, buy this whenever you have 250g to spare and won't have blue buff in the near future. CDR is an extremely important statistic.

I do not recommend these items. Seraph's would be a good source of mana, except that it provides no CDR, and is always inferior to Morellonomicon or Athene's. Building both tear and one of the CDR items gives much more mana than is necessary. If you want extra mana, better to build flask and/or Doran's ring.

I do not recommend this item. It's very good for tower pushing. However, if you want more burst at a closer distance, Lich Bane is less effective than DFG (see math section), and requires us to remain in close range to deal maximum DPS, whereas we can use the DFG active and then Valkyrie away. I see no reason to ever buy it, but it's one of the better items not in my main build, so I suppose I should include it.
I personally don't like the idea of building Lich Bane and stacking AP on Corki just because there are much better options for this style of close range champion- Kayle, Cassiopeia, etc- the list goes on. However, Corki can activate Lich Bane every time it comes off cooldown and does have a nice burst (see mathcrafting section). You can try something like this:

Mathcrafting

I'll continually update this section with some analysis of various options.

Full Level 16 Burst (DFG math)
At 40% CDR, it takes 8*0.6 = 4.8 seconds per missile stack and 33 seconds to rack up 7 missiles. The cooldown on individual casts will be 1.2*0.6 = 0.72. Shooting 7 missiles will take 5 seconds, longer than the cooldown for another, so a full burst has 8 missiles and takes about 6 seconds. This is also time for a second Phosphorus Bomb, which will also be on a 4.8 second cooldown.

Each Phosphorus Bomb will do 280+50% AP damage. Each missile will do on average (260*2+390)/3+(48+16*3)(0.2*2+0.3)/3 = 326 base damage with a (0.3*2+0.45)/3 = 0.35 ratio. Adding up 2 Phophorus Bombs and 8 Missiles we obtain our final result of 3009+380% AP.

The primary build listed would deal about (.15*2500+(360*(3.8)+3009+.21*2500)*(1/3+1.2*2/3))*100/(100+125*.6-38) =4329 damage.

Putting back in the Spectral wraith, a full combo does ((300*(3.8)+3009+.21*2500)*100/(100+125*.6-38) =3442 damage and heals for 241 HP. This is why Deathfire is core- another 900 burst damage from one item.

As a side note, the pure AP build listed would deal from close range approximately (assuming perfect execution, such as 3 lich bane procs in 6 seconds) (.15*2500+(580*(3.8+.75*3)+3009+50*3)*(1/3+1.2*2/3))*100/(100+125*.6-23) =5218 damage.

Rabadon's Deathcap
Buying Deathcap over DFG will give you an additional 114 AP (494 vs. 380). Your ults will do 326+.35*494 = 498 base damage, an increase of 8%. Your 6-second burst will become ((494*(3.8)+3009+.21*2500)*100/(100+125*.6-38) = 3950, a 10% decrease. Keep in mind that a Deathcap costs an additional 700g and requires a constant blue elixir or buff for the important 40% CDR. DFG also allows us to buy an early Fiendish Codex (although selling it only loses 246g). Both options are viable.

Lich Bane
Lich Bane is seen as core for AP Corki, and often suggested to me. I don't like it over DFG- my reasoning is as follows: As AP Corki we only want to be in auto range if 1. We are making a pick, 2. We are getting dived on. Thus, close range damage only matters in short periods. Each Lich Bane proc will do (50+340*.75)*100/(100+125*.6-38) = 222. To match the close-range burst increase of DFG, we need to hit 4 Lich Bane procs, which takes at least 8 seconds but likely more. Far too slow for us to be hitting the same target, and much longer than the 4 seconds of DFG's damage increase. Also, DFG gives more AP and that all-important 10% CDR, and the additional mana from Lich Bane is not needed with Athene's and Mp5/level seals. To use DFG effectively we need to get in 750 range once, and Lich Bane requires 550 range for an extended period. The choice is clear- DFG > Lich Bane.

AP vs. Mpen Runes
Pre-6, AP quints will give you approximately 15*0.5*100/(100+30*.92-8) = 6.3 increased damage on phosphorus bombs. Mpen quints will give you approximately 80*(100/(100+30*.92-14)-100/(100+30*.92-8) ) = 3.5 increased damage at rank 1 and 280*(100/(100+30*.92-14)-100/(100+30*.92-8) ) = 12.3 increase at rank 5, not even counting additional base damage and magic pen. The AP ratio on missiles is even lower than on bombs, and furthermore, a fixed amount of Mpen outscales AP into lategame because it is multiplicative rather than additive with the damage you have already built. Therefore Mpen is definitely better than AP.

Similar analysis holds true when comparing Mpen glyphs to AP or AP/level glyphs.

Gp10 Runes
Gp10 quints offer 3 gold per 10 seconds. The gold value of magic penetration is 30.48g (source: http://www.reignofgaming.net/blogs/a-different-view/vvinrar/22455-all-about-season-3-item-efficiency ). Thus, magic pen quints are worth 6.03*30.48 = 184 in gold value. Gp10 quints take 184/3/6 = 10.2 minutes to reach this value, and are better afterwards. It is an option to take Mpen quints (or flat AD) for a bit more early power, but Gp10 quints are the best.

Gp10 seals offer 2.25 gold per 10 seconds. Armor seals are worth 1.41*9*18 = 228 gold. Gp10 seals take 228/2.25/6 = 16.9 minutes to catch up. This is less clear-cut: early armor can be a lifesaver, but Corki is extremely good at running away and doesn't really need defensive stats. This one can go either way, but it would be great to have two rune pages- one with armor, and one without.

Early Game

As mentioned above, leave your skills unleveled until you reach lane so that you can level W first if caught.

Assuming you started Q, your level 1 trading potential is quite high, especially with a Doran's start. Be sure to pair Q's with one or more autos.

Level 2-5 is your weakest point as AP Corki. Harass with Phosphorus bomb's huge AoE and base damage whenever they go in for a CS. However, don't focus so much on harassing that you miss farm yourself. Also, try to stay out of enemy range whenever your bomb is on cooldown or out of mana as you have little damage during its cooldown. Many lanes with sustained damage will be able to out-trade you at this point, so don't feel bad if you have to play scared, focus on farming, and wait for level 6. Use your best judgement, and refer to the matchup section.

To avoid missing CS, I like to get an group of creeps low enough that a single Q will finish them off.

After level 3-4, remember that you have the option to push the lane and do wraiths quickly by jumping over the wall. This becomes easier once you hit level 6 or have Athene's/Morello/blue.

Early on your Valkyrie cooldown is quite high, so don't use it offensively unless you know where the enemy jungler is, are expecting a kill, or have flash up. Also, make sure that you always have 50 mana saved up for a Valkyrie if the jungler shows up.

Only call for ganks from your jungler pre-6 if they have good damage or you have ignite and/or AD runes+Doran. Otherwise, you probably won't get a kill, although ganking to apply pressure is fine.

Mid Game

Just like most AP carries, midgame is where you shine. Carry the game.

All sorts of general advice applies here- travel in groups, make picks, ward heavily, don't get caught, keep up your farm but try to roam and win other lanes besides your own since in solo queue everyone else is always trash. In midgame skirmishes, poke the enemy until they want to cry, but maintain 5 or 6 missile stacks in case they initiate on you.

If you have nowhere to roam and your lane is pushed, steal your entire jungle while spamming laugh (protip: put it on an easily accessible hotkey). Don't forget to lasthit the big wraith/wolf if your jungler tries to take what is rightfully yours, obviously. If I am losing lane, I do my best to catch up simply by farming the entire jungle- I've overcome a 30 CS deficit in this way.

Let your jungler know that you very much want the second blue buff, and that the third would be nice as well. After that, you can continue to take them if carrying or skipped Athene's, or give them to the jungler or somebody else who needs them more. Without blue buff, just be sure not to spam too many Phosphorus Bombs, as that's your most costly spell. However, the CDR is really nice on you so make sure to get the second blue. If getting blue buffs all game, it's likely best to skip Fiendish Codex.

Be aware of your level 6/11/16 power spikes. If you're level 10 or 15 and deal a significant portion of your team's damage (not uncommon), tell your team to avoid fights until you hit 11/16. This also holds if you are about to finish a big core item, especially Void or Liandry's.

Late Game

For an AP Carry, you scale very well into lategame, especially with a tanky/CC heavy team to back you up. Your burst is weaker lategame than a lot of AP's, but your sustained AoE damage output with your completed magic penetration build and the % health DoT from Liandry's is fantastic.

You can't really duel bruisers unless ahead, but you can put out large damage totals from safety. If in a safe scenario to do so, you can poke a bruiser with your missiles and essentially 1v1 him in this way, you just can't afford to take the same sort of damage.

Stay with your team constantly, unless you're leaving to quickly farm a wave with your AoE. You don't want to get caught, although your Valkyrie makes this not as easy for you as other mages. Ryali's is also helpful to kite and escape.

Communicate to your team that you need to poke before engaging for a teamfight, or else you are wasting your potential (ignore this if their team has stronger poke or if you are winning hard enough).

However, make sure not to run out of rockets- once again, keep at least 5 or 6 handy if a teamfight seems like it may break out. It's easier to land missiles in a teamfight, when enemies may be grouped in AoE range and are less likely to focus on dodging your missile spam than in a poke scenario.

If there's any chance that an enemy is waiting in a bush, use your R (or Q) to check it before getting exploded. R can check bushes at a longer range, since you will see the explosion if it collides with something- this is why R is usually a better idea.

Remember that lategame you can easily solo dragon, and on blue side you can Valkyrie over the wall if caught by the other team. Remember to spam laugh first.

Regarding baron: if your team is attempting it with a possible steal, note that you will likely be vulnerable to the other team as you cannot position yourself behind your tanks without trapping yourself in the baron pit. A smart enemy team will pick you off easily.

On the other hand: if the enemy team is attempting baron, they will be forced to clump together and you can easily poke them from outside the pit. Just be ready to Valkyrie away if they peel off of Baron for you, and be aware of what long-range CC or intiations are available to the other team. For example, Zac or Leona can catch you off guard if not careful, even from what seems like a safe distance.

Team Fights

You are very squishy. Poke while keeping your distance, and think long and hard before using Valkyrie offensively as it is your lifeline. Even if you think it would be easy to just jump in and clean up, it is quite easy to underestimate the enemy's ability to just turn and kill you before running or dying themselves.

Play somewhat passively. Remember that your life is not usually worth trading away lategame- you are a hypercarry, and can easily stop a baron or tower attempt with your long range.

Try to aim your missiles at squishy carries and large groups. However, like an AD carry, you can't always pick the best target without overextending, so be happy with doing damage at all. However, don't blow all seven missiles on a pure tank and have nothing left for anybody else.

Make sure to kite and reposition yourself in the short time between your spells. Don't spam all 7 missiles right away if you don't have a proper angle of attack- move around first so that you can sneak missiles at their carries.

When dived on: if not in danger of death, kite backwards while using your Q, E, and R (and DFG) for damage. You can Valkyrie away and damage from afar, but remember that you can only do so once every 8.4 seconds. Furthermore, in solo queue be wary of escaping too far back behind your team, as you will lose a duel against an assassin if you run away from your peel.

Generally, save your Phosphorus Bomb and DFG for people diving you rather than overextending to get in range, but when in highly favorable situations feel free to break this rule. Teamfights are your time to shine, and it's okay to take some risks in order to carry.

Despite your lack of CC, you can also play a peeling role- if your fed ADC is under attack by an assasin, feel free to blow your combo on them so that the ADC can survive and continue doing damage.

An important strategy one should consider to maximize AP Corki's teamfight DPS: flanking. Say that you're facing a fed Vayne, but she is well protected by a frontline of Renekton and Nasus who both have spirit visages. You clearly do not want to blow all of your missiles on them, but it can be difficult to shoot around the tanks. What you can do is wait for them to initiate on your tankline, then approach from the side and shoot at the carries from an angle. Valkyrie allows you to easily escape if collapsed upon.

Matchups

So I may or may not finish a complete matchup section, but I thought I'd start one because Cablecarento wrote up a good chunk for me. Huge thanks to him! Anybody is welcome to contribute if they want, just add me ingame.

First thing to know: AP Corki has no counters. There are easy lanes, and there are lanes where you can potentially lose. The only things we don't like are sustain, tankiness, and heavy damage+CC in both the laner and jungler. But these things are not dealbreaking- in a worst case scenario, we simply farm using missiles, always ready to Valkyrie away from danger, and scale well into lategame. I've discussed this with other AP Corki players, and nobody has been able to come up with somebody who can consistently kill AP Corki or stop him from farming, as long as he plays suitably defensive.

Lane Matchups

Nidalee: This is my favorite AP Corki counterpick. It's not a true counter by any means, but AP Nidalee is strong against Corki both in lane and overall. Neither one has much kill potential on the other, but it is much easier for Nidalee to force Corki out of lane because of her heal, and she can get kills if Corki sticks around after getting speared. After the laning phase, Nidalee is one of the few champs that pokes as hard as Corki (less damage, but equally impactful through single target burst), and also negates some of Corki's poke with her heals. My recommendation is to start with a flask, and buy a bunch of potions every back on top of that during late laning phase so that you don't have to back after she hits a single spear. Also, in general you will want to force hard engages rather than poking like normal.Run setup 1.

Ryze: Starting with a ward is a good idea because of his W root and early strength against you. You lose trades from levels 2-5, so do your best to farm while retaliating when he gets in range. You slightly outrange him, so it is possible to Q him without eating his Q if he is going for a CS. After 6 you outrange him by a great deal, and can easily bully him out of lane. He will often run teleport, so running teleport to counter this is an option. Other good summoner spells are barrier, ignite, and cleanse.Run setup 1.

Twisted Fate: If you dodge his Q's, the lane will be a breeze. Don't stand in the line of your minions, or the diagonal path his cards would take if he Q'd your minions. Poke him down without getting in range for a gold card, and if he does gold card you, using Valkyrie can often get you away from any q's that he throws, but only do this when you can spare the mana. Post 6 you can bully him out of lane. If you get him low enough, he cannot teleport to another lane because he can easily die. Run ignite for kills, or teleport to follow his roam. Run setup 2.

Lee Sin: If you dodge his Q's there is nothing he can do in lane. Check to see if he started red pot, and don't get baited. Lee has a hard time catching you out in the mid-late game due to your Valkyrie, but it is possible so always be careful. Other than that, poke him down constantly and don't get caught. I recommend barrier for this lane, as Lee is still rather bursty and barrier can save you. Building a Seeker's Armguard is also an option.Run setup 2.

Heimerdinger: The Donger will either max his Q or his W. If you notice that his rockets are doing no damage at all, then simply focus on farming and killing his turrets, both of which you do extremely well. If his rockets instead do a quarter of your health in damage, then treat the lane like Master Yi. If there are two or less minions in the lane, do not get near him. Instead, focus on harrassing when the minion waves are up and go in on him whenever it's safe enough. Run setup 1 or 2.

Ahri: She's tricky in that she's one of the few champs that has more gapclosers than you. Always keep your movements unpredictable, and especially be sure to dodge her charm. If you're afraid of getting killed just farm with your missiles and have your trigger finger ready to Valkyrie to dodge charm. Starting with a ward and taking cleanse are not bad ideas.Run setup 1 or 2.

Kha'zix: This guy is actually not so bad. Starting with cloth armor is a good idea, or you can easily get blown up. If you have some armor, however, you can easily poke and bully him even pre-6. Starting AD quints and getting a Doran's Blade is not a bad idea if you're ballsy. Just don't trade with him in melee range- you will lose. Save your jump to counter his jump, and when his is down don't hesitate to whack him for a few seconds. Take barrier or ignite.Run setup 1 or 2.

Pantheon: Start with armor seals and a cloth armor. After this, as long as you don't eat too many spears you are completely safe to just farm and poke him down at level 6. You will easily outscale this matchup, as long as Panth doesn't get too fed by roaming- call MIA's quickly and loudly, and then either shove your lane or follow him. However, be aware that he will have more impact in early skirmishes, so try to avoid them. Consider taking teleport to counter his roam, but I'd probably take barrier.Run setup 1.

Kennen: Not a bad matchup. He generally outtrades you pre-6, but he probably won't kill you if you play carefully. Post-6, you can easily poke him down with missiles. However, don't get cocky- if he ults, Valkyrie out of it immediately or he will probably kill you. For this reason, don't stay too close to him post-6 with marks of the storm on you, or he can proc them for the stun and ult while you're stuck. Run setup 1.

Kog'maw: This is a skill matchup, but heavily in your favor. AP Kog loses most lanes, and you are no exception. Start Doran's Blade and bully him heavily pre-6. After you get your ults, it becomes a battle of who can land more skillshots, and you will probably win. His ults have longer range, especially at level 11 and 16, but yours are easier to land in lane. Play aggressively to shut him down, as you have kill potential on him and he does not have kill potential on you due to Valkyrie. Also, a Kog allowed to freefarm will tear apart your team unless you have strong dive.Run setup 2.

Lissandra:You outdamage her throughout the game. Furthermore, her gapcloser is highly telegraphed, and to stay on the safe side you can simply use yours whenever she uses hers, which has a higher mana cost and cooldown. Just be careful not to get caught in her CC during a jungler gank, and this should be an easy lane. Lissandra is hard to kill, so just shove your lane and roam or farm your jungle.Run setup 2.

Jarvan IV: An underrated mid, and one of my favorites. This matchup is quite winnable, but has the potential to go very wrong if you aren't careful. Starting with Doran's is not an option, as the only time you can safely bully him is level 1, and afterwards he will simply dunk you if you get that close. Especially at level 2, but also at level 6 and through the entire midgame, his burst and gapclosing potential is extremely high. Start with cloth armor and 5 health potions, and run barrier. If he is using his E-Q combo aggressively, ask your jungler to camp him for easy kills. He has high utility, but his damage falls off so just push and farm and wait for lategame.Run setup 1.

Zed: This is a pretty easy matchup. Start with Doran's and bully him pre-6. Post-6, you can bully him even harder, and can immediately jump away whenever he ults you. Pick up a cloth armor for laning, to sell or turn into Zhonya's if he gets fed, and don't get caught in a jungler gank when he has his ult.Run setup 2.

Orianna: This is a skill matchup, and can be pretty tricky. She can trade autos with you, and will win extended trades. The range on her ball is higher than your Q, and high enough that she can chunk you post-6 if you're not careful. If she's good, she can even shield your missile harass. Poke her out of lane, or shove and get your farm on. Run setup 1.

Fizz: AP Corki is a very good pick against Fizz. Start with Doran's, Q-auto him whenever he tries to farm, win lane. Don't let him snowball, and be careful of his damage if he tries to kill you.Run setup 2.

Yorick: Not a standard mid laner, but a difficult matchup. He has high harass and sustain, and his ghouls will block your rockets, making him hard to trade with. He can't kill you, however, so merely farm up, play it safe, and outscale him lategame. Good pick against AP Corki.Run setup 1.

Kayle: Tricky matchup. You can never trade autos, even with a Doran's start, and if you get in Q range from level two onward she can punish you. She also has a heal, so does well against you even post-6. Run setup 1.

Vladimir: I haven't played this matchup, but I expect Vlad to be a very strong pick against Corki. Vlad will likely be able to sustain through your harass both pre-6 and post-6, and is manaless. Furthermore, he scales just as well into lategame as Corki does. Shove your lane and keep up by farming your jungle and roaming. This is one of the few matchups where I might buy both a flask and Athene's.Run setup 1 or 2.

Jayce: I used to consider this a hard matchup. The trick here is to start with a Crystalline Flask into Morellonomicon, with optional cloth armor or seeker's armguard if he's ahead or facing a heavy AD team. A Doran's start is fine, but auto range is generally unsafe because he can use his empowered Q then melee form combo. With this setup, you will be able to sustain his poke and force him out of lane. Just remember to hide behind creeps and keep your movement unpredictable to dodge shock blasts.Run setup 1.

Junglers

Jarvan IV: This guy has two gapclosers post-6. You only have one. Plan accordingly, and unless you dodge his flagtoss completely with Valkyrie just wait until after you get knocked up so that it isn't interrupted, leaving you with nothing. Also, watch out for his early burst damage.

Sejuani: With a gapcloser, a slow, and a longranged stun Sejuani is one of the champs that has the potential to kill you when backed up with damage.

Nautilus: Not super threatening, but if you get caught in his CC chain when he has backup you will die.

Hecarim: If he comes at you from behind then you cannot W behind him. He can knock you out of your W and send you nowhere. Instead W diagonally backwards, or even just sideways. It will send you flying sideways, and hopefully away from the enemy mid laner. Alternatively, wait for his knockback to proc, then use your escape afterwards. If he comes from the side or you see him coming just W backwards like always.

Amumu: Valkyrie away from his Q's, no problem. In teamfights, just make sure not to get into close range until his ult has been used already.

Final Comments

That's it! I have no idea if AP Corki is viable in pro play, but in solo queue he is an extremely strong pick. I expect that he may start showing up in the pro scene once the currently popular midlane assassins get nerfed- particularly Ahri, who can go even in lane and outroam him.

I hope you enjoyed the guide! Comment if you have any questions/suggestions. If you're Gold league or higher, feel free to write up any matchups you encounter, and I may include them.

Consider yourself spanked, nugget!

Comments

Well I am trying to get to gold, and AP Corki is carrying me up in Silver 1 right now. All I do is get athene's\liandrys\rylais and poke the hell out of the other team. Currently at an 80% win ratio. If I climb into gold with him I'll update this post. Great guide BTW.

The best way to play him will be with Lichbane now, since otherwise we'll have no burst, and his ult cooldown is exactly that of lichbane. AP Corki might stay viable for solo queue, but I'm almost positive there won't be any reason to pick him

However: apparently there are more Corki changes coming sometime in the form of a rework to his Q. So not all hope is lost yet

Against Kassadin, it is surprisingly easy, especially with Dorans start. Pre-6 there really is nothing he can do. If he tries to harrass you with q, you trade back some autos while denying him any farm. If he farms with q, you can shut him down completely. If you shut him down enough during the early levels he should be also easy past-6. If he wants to farm meelee, you can easily hit him with one or two rockets, and if he jumps on you you can basically just wait until the silence is over and trade double the damage back.

You should REALLY get this approved. Probably the best quality guide I've ever seen. In contrast to most guides that get approved, this one, if it were to get approved, would actually contain a lot of fact instead of flashiness, pointless imagery and typically poor item builds. +1.

Hey, I have a suggestion for improveing your guide. First off, the part at the top of your guide where you have items listed, it should be shorter and easier to understand. That section is where you make a quick list of items with very few details. The details should be placed in the item section of your guide. Also, your item section is a little hard to read. You can clean it by talking about each item by itself.